Mechanical alloying technique is used for the decrystallization of Fe100-xBx samples with soft magnetic character. Wide angle X-ray scattering (WAXS) and differential scanning calorimetry have been used to monitor the decrystallization kinetics, whose time dependence can be fitted by a stretched exponential function. In all the samples, milling times of around 500 h lead to very low crystallinity percentages (around 5%). This residual crystalline phase corresponds to a mixture of FeB and Fe2B phases, and the α-Fe phase almost disappeared at the same time. During the decrystallization, the grain size of the α-Fe phase changes appreciably from 40 down to 15 nm. Magnetic properties of the samples in their final lowest crystalline state showed different behaviours for the samples rich in boron or in iron.

The authors thank the spanish Ministerio de Ciencia y Tecnología for partial finantial support (project MAT2001-0082-C04-04).